Surface plasmon polaritons launched by nano-emitters are imaged in the near field

Abstract:

Surface plasmon polaritons (SPPs) are fascinating electromagnetic waves that propagate along the interface between a metal and a dielectric. These waves exhibit unique properties, such as strong confinement and high sensitivity to the surrounding environment, making them valuable for various applications in nanophotonics, sensing, and imaging. This paper explores the near-field imaging of SPPs launched by nano-emitters, discussing the principles, techniques, and recent advancements in this field. The combination of nanoscale emitters and near-field imaging allows for high-resolution imaging and characterization of SPPs, enabling a deeper understanding of their behavior and potential applications.

1. Introduction:
   Surface plasmon polaritons (SPPs) arise from the coupling between light and collective oscillations of free electrons at a metal-dielectric interface. These waves have unique properties, including strong confinement, long propagation distances, and the ability to concentrate light below the diffraction limit. Nano-emitters, such as quantum dots, metallic nanoparticles, and organic molecules, can efficiently launch SPPs and serve as localized sources for near-field imaging experiments. In this context, near-field imaging techniques provide a means to study and manipulate SPPs with high spatial resolution.

2. Near-Field Imaging Techniques:
   This section explores various near-field imaging techniques used to visualize SPPs launched by nano-emitters. Near-field scanning optical microscopy (NSOM), scanning probe microscopy (SPM), and aperture-based techniques, such as scattering-type scanning near-field optical microscopy (s-SNOM), are discussed in detail. These techniques leverage the interaction between the near-field probe and the SPPs to achieve sub-diffraction-limited spatial resolution and image the electromagnetic field distributions.

3. Imaging SPPs Launched by Nano-Emitters:
   The successful imaging of SPPs launched by nano-emitters relies on the precise positioning of the emitter, efficient excitation of SPPs, and the detection of their near-field signatures. This section describes various nano-emitters used for SPP excitation, including plasmonic antennas, tapered fiber tips, and metallic nanoparticles. The interaction between the nano-emitter and the SPPs is analyzed, emphasizing the importance of understanding the emitter-SPP coupling mechanisms for optimal imaging.

4. Characterization and Manipulation of SPPs:
   Near-field imaging not only enables visualization of SPPs but also facilitates their characterization and manipulation. This section discusses spectroscopic techniques, such as scattering spectroscopy and energy-resolved near-field imaging, which provide valuable information about the SPP dispersion and propagation properties. Furthermore, the control and manipulation of SPPs through near-field imaging techniques, such as tip-enhanced Raman spectroscopy (TERS) and plasmonic tweezers, are explored, highlighting their potential for applications in sensing and nanophotonics.

5. Recent Advancements and Future Directions:
   Recent advancements in near-field imaging of SPPs launched by nano-emitters are presented, including developments in nanoscale light sources, novel probe designs, and enhanced imaging modalities. Additionally, future directions and emerging trends in this field are discussed, such as the integration of SPP imaging with other imaging modalities, the exploration of hybrid plasmonic systems, and the investigation of SPPs in complex and non-linear materials.

6. Conclusion:
   Near-field imaging of SPPs launched by nano-emitters has emerged as a powerful tool for studying the behavior and properties of these unique electromagnetic waves. By combining nanoscale emitters and high-resolution imaging techniques, researchers can gain valuable insights into SPP propagation, localization, and interaction with nanostructures. The continued advancements in this field hold great promise for the development of new applications in nanophotonics, sensing, and imaging at the nanoscale.